Recently, a hybrid vehicle and an electric vehicle have received attention as a vehicle giving consideration to environment. The hybrid vehicle adopts, as a source of mechanical power, a motor driven by a DC power supply through an inverter, in addition to an engine that has been conventionally used as such a source of mechanical power. In the hybrid vehicle, more specifically, the engine is driven to obtain mechanical power. Further, the inverter converts a DC voltage generated by the DC power supply to an AC voltage, and the motor is rotated by the converted AC voltage to obtain mechanical power. On the other hand, the electric vehicle adopts, as a source of mechanical power, a motor driven by a DC power supply through an inverter.
An intelligent power module (IPM) to be installed on the hybrid vehicle or the electric vehicle switches a semiconductor switching element (a power semiconductor element) such as an IGBT (Insulated Gate Bipolar Transistor) at high speed, thereby converting DC power supplied from the DC power supply to AC power; thus, the motor is driven (refer to, for example, Japanese Patent Laying-Open No. 2003-9507, Japanese Patent Laying-Open No. 2005-33882, Japanese Patent Laying-Open No. 11-299056 and Japanese Patent Laying-Open No. 11-187542).
For example, Japanese Patent Laying-Open No. 2003-9507 discloses a switching circuit that includes a bus bar serving as a conductor for connecting a switching element to a power supply or a load. In such a switching circuit, different types of bus bars are fixed onto a base while being fastened to each other with an insulator being interposed therebetween.
Herein, each bus bar to be used herein is a metal member serving as a conductor having a wide sectional area which is sufficient to flow a current between the power supply or the load and the switching circuit. Then, the power supply positive electrode side bus bar connected to a positive electrode of the power supply and the power supply negative electrode side bus bar connected to a negative electrode of the power supply are fixed onto the base while being integrally fastened to each other with the insulator being interposed therebetween.
In the switching circuit described above, however, the bus bars each of which is a metal member are arranged while overlapping with each other in a normal direction of the base with the insulator being interposed therebetween. Consequently, there arises a problem that the switching circuit increases in size in the normal direction of the base. This problem hinders miniaturization of the switching circuit in the normal direction although miniaturization of the IPM is demanded strongly.
Moreover, Japanese Patent Laying-Open No. 2003-9507 discloses a connection relation between a switching element and a power supply side bus bar and a connection relation between a switching element and a load side bus bar (a U-phase side bus bar, a V-phase side bus bar, a W-phase side bus bar), but does not disclose an arrangement of an outlet for a signal line through which each switching element receives a signal for controls a switching operation. In order to miniaturize the IPM, therefore, sufficient consideration must be given to the arrangement of the outlet for the signal line.
The present invention has been devised to solve the problems described above, and an object thereof is to provide a semiconductor module capable of achieving miniaturization, and a hybrid vehicle drive device including the semiconductor module.